Detection of E. coli, Coliforms & Enterobacteriaceae

For the enrichment, isolation and enumeration of Escherichia coli, coliform bacteria and Enterobacteriaceae in the course of food and beverage testing, Merck maintains a broad range of granulated, dehydrated culture media (DCM) in a variety of formulations. Our granulated media are not only convenient but also safe, and they meet the highest industry performance standards as described in ISO 11133. These media cause significantly less dust than powdered media, leading to less inhalation of hazardous media components that may cause allergic responses. In addition, they minimize contamination of the lab environment.

Like all Merck media, our culture media for E. coli, coliforms and Enterobacteriaceae are quality controlled according to stringent standards. This guarantees the high quality and consistency of our media products.

Enterobacteriaceae: The Most Well-Known Family of Bacteria

There are about 20 genera in the family Enterobacteriaceae, which include E. coli and the group of coliform bacteria. Members of the family are gram-negative and rod-shaped. They are facultative anaerobes that ferment sugar to produce lactic acid. Enterobacteriaceae are unable to form spores. Most species have flagella to move. Numerous Enterobacteriaceae are found in the intestines of humans and other animals, some occur in water or soil whereas others are parasites on animals and plants.

Most Enterobacteriaceae involve peritrichous type I fimbriae in the adhesion of the bacterial cells to their hosts. Some species produce endotoxins that are stored in the cells’ cytoplasm and released when the cells die and the cell walls disintegrate. When many dead bacterial cells release their endotoxins into the blood stream, a so-called endotoxic shock may occur, which can be fatal.

Coliform Bacteria: The Broader Group of Indicators

Coliforms are gram-negative, facultative anaerobic, rod-shaped bacteria. They are common in the feces of warm-blooded animals and can be found in aquatic environments, in soil and on vegetation. Coliform bacteria do not usually trigger serious illnesses. Due to the fact that they are easy to culture, their presence is used to indicate that more pathogenic organisms of fecal origin may be present.

Escherichia coli: An Established Indicator Organism

E. coli is a gram-negative, facultative anaerobic, rod-shaped bacterium. This bacterium is common in the lower intestine of warm-blooded animals. Most species of E. coli are harmless. They can even benefit their hosts by producing vitamin K2 and preventing pathogenic bacteria from establishing themselves within the intestine. However, some strains can cause serious food poisoning in humans and are sometimes the reason for product recalls due to food contamination. Fecal-oral transmission is the most common route through which pathogenic organisms cause disease.